Patent document 1 discloses a technology for detecting the acceleration of a mobile terminal, judging the posture of the mobile terminal based on the detected acceleration, and changing the displayed direction of a screen that is being displayed on a display unit based on the judged posture.
The mobile terminal disclosed in Patent document 1 is occasionally liable to have the displayed direction of the screen changed suddenly because it tends to detect an unintended acceleration on account of shaking of the mobile terminal (due to shaking of the hand carrying the mobile terminal, and operation of the vibrator) and external causes (due to operation of the mobile terminal on a vehicle).
If the user is simply viewing the screen at this time, then the user can view the screen in the original displayed direction by moving the mobile terminal back to its original posture. However, if the user is operating the mobile terminal, the user is likely to make a mistake because of the sudden change of the displayed direction of the screen.
Patent document 2 discloses a technology for stopping the displayed direction of the screen from changing while the user is speaking on the mobile terminal. However, the technology is unable to stop the displayed direction of the screen from changing at other times than while the user is speaking on the mobile terminal.